U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2014-3089 

February 2015

Prepared in cooperation with the Louisiana Department of Transportation and Development 

Water Resources of La Salle Parish, Louisiana

Introduction

Information concerning the availability, use, and quality of 

water in La Salle Parish, Louisiana (fig. 1), is critical for proper 

water-supply management. The purpose of this fact sheet is to 

present information that can be used by water managers, parish 

residents, and others for stewardship of this vital resource. 

Information on the availability, past and current use, use trends, 

and water quality from groundwater and surface-water sources 

in the parish is presented. Previously published reports (see 

References Cited section) and data stored in the U.S. Geological 

Survey’s National Water Information System (http://waterdata.

usgs.gov/nwis) are the primary sources of the information 

presented here. 

In 2010, about 2.40 million gallons per day (Mgal/d) 

of water were withdrawn in La Salle Parish, including about

2.29 Mgal/d from groundwater sources and 0.10 Mgal/d from 

surface-water sources1

 (table 1). Categories of use included 

public supply, rural domestic, livestock, general irrigation, and 

aquaculture (table 2). Water-use data collected at 5-year intervals 

from 1960 to 2010 (fig. 2) indicated that water withdrawals 

peaked in 1960. 

1

Water-withdrawal data are based on estimated or reported site-specific data 

and aggregated data, which are distributed to sources. For a full description 

of water-use estimate methodology, see “Data Collection” in Sargent (2011). 

Tabulation of numbers in text and tables may result in different totals because of 

rounding; nonrounded numbers are used for calculation of totals. 

La-254A

Olla

Jena

WINN

PARISH

GRANT

PARISH

RAPIDES

PARISH

AVOYELLES

PARISH

LA SALLE

PARISH

CATAHOULA

PARISH

CALDWELL

PARISH

Cockfield

aquifer

Catahoula

aquifer

Catahoula

aquifer

Williamson Creek

aquifer

Carnahan Bayou

aquifer

Carnahan Bayou

aquifer

165

84

28

Urania

Tullos

Bayou Funny Louis

Catahoula Lake

Saline Lake

Muddy Bayou

Little Chickasaw

Creek

Hemphill

Creek

French Fork

Little River

Chickasaw Creek

Big Saline

Bayou

Trout Creek

Mississippi River

alluvial aquifer

Nebo

Trout

Rochelle

Little River A

A'

TEXAS

ARKANSAS MISSISSIPPI

LOUISIANA

LA SALLE

PARISH

GULF OF MEXICO

EXPLANATION

Approximate altitude of base of fresh

 groundwater, in feet below National

 Geodetic Vertical Datum of 1929 (NGVD 29)

 (modified from Smoot, 1988)

 Above NGVD 29

 0 to 49

 50 to 499

 500 to 899

Approximate area where no major aquifer 

 contains freshwater

Approximate area where intermediate sands 

 contain saltwater

Approximate boundary of area showing deepest 

 freshwater contained within Mississippi River 

 alluvial, Williamson Creek, Carnahan Bayou, 

 Catahoula, and Cockfield aquifers 

Line of section (see fig. 3)

Well for which hydrograph is shown

 (see fig. 4)

U.S. Geological Survey surface-water 

 discharge site and number

U.S. Geological Survey surface-water 

 quality site and number (see table 4)

La-124

A'A

07372500

07372200

O

C

312815092092000

312910092072000

313355092042000

07372500

07373250

La-172

La-124

07372200

C

C

O

O O

O

C

92°10'

92°20'

92°00'

31°50'

31°40'

31°30'

31°20'

10 KILOMETERS

0

0 2 4 6 8

Base modified from U.S. Geological Survey digital data 2 4 6 8 10 MILES

Albers Equal-Area Conic projection

North American Datum of 1983

Figure 1. Location of study area, La Salle Parish, Louisiana.
Table 1. Water withdrawals, in million gallons per day, by source 

in La Salle Parish, Louisiana, 2010 (Sargent, 2011; B.P. Sargent, 

unpub. data, 2011). 

[<, less than]

Aquifer or surface-water 

body Groundwater Surface water

Mississippi River alluvial 

aquifer

<0.003

Upland terrace aquifer 1.28

Catahoula aquifer 0.16

Cockfield aquifer 0.86

Miscellaneous streams 

and ponds

0.10

Total 2.29 0.10

Table 2. Water withdrawals, in million gallons per day, by 

use category in La Salle Parish, Louisiana, 2010 (modified from 

Sargent, 2011).

Use category Groundwater Surface 

water Total

Public supply 2.18 0.00 2.18

Rural domestic 0.06 0.00 0.06

Livestock 0.01 0.03 0.03

General irrigation 0.00 0.08 0.08

Aquaculture 0.06 0.00 0.06

Total 2.29 0.10 2.40

0

1

2

3

4

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Year

Groundwater

Surface water

EXPLANATION

Annual withdrawals, in million gallons per day

1960–2010 (Sargent, 2011).

Figure 2. Water withdrawals in La Salle Parish, Louisiana, 

Groundwater Resources

Fresh groundwater (water with a chloride concentration of 

250 milligrams per liter [mg/L] or less) is generally available in 

La Salle Parish along the northern parish line and in central and 

southern parts of the parish (fig. 1). Where present, the base of 

freshwater is generally at depths ranging from near the National 

Geodetic Vertical Datum of 1929 (NGVD 29) to about 800 feet 

(ft) below NGVD 29 (Smoot, 1988). The primary sources of 

fresh groundwater in La Salle Parish are the Mississippi River 

alluvial, Upland terrace, Catahoula, and Cockfield aquifers (table 

1). The Williamson Creek and Carnahan Bayou aquifers could 

also be sources of fresh groundwater in small areas of southern 

La Salle Parish (fig. 1); however, they will not be discussed 

further because no wells have been reported as screened in these 

aquifers. Recharge to aquifers in the parish is from precipitation, 

leakage from adjacent aquifers, and seasonal flow from streams. 

Discharge from the aquifers is by natural seasonal flow into 

streams, evapotranspiration, leakage into adjacent aquifers, and 

withdrawals from wells. 

State well-registration records listed 168 active water wells 

screened in the primary groundwater sources in La Salle Parish 

in 2014, including 107 domestic, 35 public supply, 20 industrial, 

and 6 irrigation. In 2010, categories of use for groundwater 

withdrawals included public supply, rural domestic, livestock, and 

aquaculture (table 2) (Louisiana Department of Natural Resources, 

2014). 

Mississippi River Alluvial Aquifer

The Mississippi River alluvial aquifer is present near land 

surface in an area extending from about 2 miles (mi) northwest of 

Catahoula Lake southward to the southern tip of La Salle Parish. 

The aquifer comprises basal sand and gravel components of 

alluvial deposits that grade upward to silt and clay. The alluvial 

deposits composing the Mississippi River alluvial aquifer range 

in thickness from 150 to 200 ft and overlie the Williamson 

Creek, Carnahan Bayou, and Catahoula aquifers. In La Salle 

Parish, groundwater in the Mississippi River alluvial aquifer is 

unconfined or semiconfined and generally moves northeast toward 

a topographic low near the eastern end of Catahoula Lake (Seanor 

and Smoot, 1995). Infiltration of precipitation through the surficial 

silts and clays is the primary source of recharge, with additional 

recharge coming from underlying aquifers and seasonal flow from 

streams (Whitfield, 1975).

State well-registration records listed 9 active wells screened 

in the Mississippi River alluvial aquifer in La Salle Parish in 2014, 

including 5 domestic, 2 irrigation, and 2 industrial. Well depths 

ranged from 24 to 220 ft below land surface. Reported yields from 

wells screened in the Mississippi River alluvial aquifer in La Salle 

Parish ranged from 100 to 1,500 gallons per minute (gal/min; 

Louisiana Department of Natural Resources, 2014). 

Upland Terrace Aquifer

The Upland terrace aquifer outcrops at land surface in 

much of central La Salle Parish, where it overlies the Catahoula 

aquifer (fig. 3), and in small areas in northern La Salle Parish, 

where it overlies the Cockfield aquifer and Vicksburg-Jackson 

confining layer. The Upland terrace aquifer comprises basal 

sands and gravels of terrace deposits that grade upward to silt 
500

NGVD 29

-500

-1,000

-1,500

-2,000

-2,500

0 5

5 10 KILOMETERS

10 MILES

0

NORTHWEST

A

SOUTHEAST

A’

FEET

500

NGVD 29

-500

-1,000

-1,500

-2,000

-2,500

FEET

Approximate land surface

VERTICAL SCALE GREATLY EXAGGERATED

Vertical datum is National Geodetic Vertical Datum of 1929 (NGVD 29)

Cook Mountain confining layer

Vicksburg-Jackson confining layer

Catahoula aquifer

Deeper aquifers in the parish contain saltwater

Cockfield aquifer

Catahoula

Lake basin

Upland

terrace

aquifer Mississippi River 

alluvial aquifer

Bayou Funny Louis

Trout Creek Hemphill 

Creek EXPLANATION

Base of freshwater

and clay. In La Salle Parish, the thickness of the terrace deposits 

generally ranges from 30 to 50 ft in small outcrops in northern 

La Salle Parish and from 100 to 150 ft in the main outcrop area 

in central parts of the parish (Sloss and others, 1961). The aquifer 

is recharged by precipitation and is generally under water-table 

(unconfined) conditions. Groundwater in the aquifer moves from 

topographically high positions to local stream valleys (Rollo, 

1960). The aquifer generally contains freshwater, but in the 

topographically low areas near Catahoula Lake, saltwater (water 

with a chloride concentration greater than 250 mg/L) is present. 

State well-registration records listed 82 active water wells 

screened in the Upland terrace aquifer in La Salle Parish in 

2014, including 61 domestic, 17 public supply, 3 irrigation, and 

1 industrial. Well depths ranged from 8 to 227 ft below land 

surface. Reported yields from wells screened in the Upland terrace 

aquifer in La Salle Parish ranged from 2 to 350 gal/min (Louisiana 

Department of Natural Resources, 2014). In 2010, withdrawals 

from the Upland terrace aquifer in La Salle Parish totaled about 

1.28 Mgal/d and included about 1.25 Mgal/d for public supply and 

0.03 Mgal/d for rural-domestic use. Freshwater from the Upland 

terrace aquifer is generally soft2

 and generally does not exceed the 

U.S. Environmental Protection Agency’s Secondary Maximum 

Contaminant Levels (SMCLs)3

 for color or concentrations of iron, 

manganese, and dissolved solids (table 3). 

Catahoula Aquifer

The Catahoula aquifer outcrops at land surface or subcrops 

beneath terrace deposits across central La Salle Parish in a 

southwest-to-northeast direction. In La Salle Parish, the base of 

freshwater in the Catahoula aquifer generally ranges from near the 

2

Hardness ranges, expressed as milligrams per liter of calcium carbonate, are 

as follows: 0–60, soft; 61–120, moderately hard; 121–180, hard; greater than 180, 

very hard (Hem, 1985). 3

The SMCLs are nonenforceable Federal guidelines regarding cosmetic effects 

(such as tooth or skin discoloration) or aesthetic effects (such as taste, odor, or 

color) of drinking water. At high concentrations or values, health implications as 

well as aesthetic degradation may result. SMCLs were established as guidelines 

for the States by the U.S. Environmental Protection Agency (1992). 

Figure 3. Generalized 

northwest-to-southeast 

hydrogeologic section 

through La Salle Parish, 

Louisiana, showing 

aquifer and confining 

layer intervals (individual 

sand and clay layers not 

shown; modified from Fisk, 

1938). Trace of section 

shown on figure 1.

NGVD 29 in central areas to about 800 ft below NGVD 29 near 

the southern end of the parish (fig. 1). In the southwestern corner 

of the parish, the Catahoula aquifer contains only saltwater (fig. 1). 

The Catahoula aquifer is recharged by infiltration of 

precipitation in outcrop areas within the parish and flow from the 

overlying Upland terrace aquifer. Much of the water entering the 

aquifer is discharged to nearby streams, but some may be lost to 

evapotranspiration. Water that is not discharged locally moves 

downgradient southward toward discharge areas at lower altitudes 

and toward the Little River Valley (Martin and Whiteman, 1986). 

Water levels in the Catahoula aquifer in La Salle Parish fluctuate 

annually but showed little increase or decrease from 2002 to 2012, 

as illustrated by water levels in well La-172 (fig. 4), located in the 

outcrop area about 4 mi north of Jena, and in well La-124, located 

about 6 mi south of Jena (fig. 1).

State well-registration records listed 38 active water wells 

screened in the Catahoula aquifer in La Salle Parish in 2014, 

including 25 domestic, 9 public supply, 3 industrial, and 1 

irrigation. Well depths ranged from 21 to 873 ft below land 

surface. Reported yields from wells screened in the Catahoula 

aquifer in La Salle Parish ranged from 24 to 350 gal/min 

(Louisiana Department of Natural Resources, 2014). In 2010, 

withdrawals from the Catahoula aquifer in La Salle Parish totaled 

about 0.16 Mgal/d and included about 0.08 Mgal/d for public 

supply, 0.05 Mgal/d for aquaculture, and 0.03 Mgal/d for ruraldomestic use and livestock. A statistical summary of selected 

water-quality characteristics for freshwater samples collected from 

44 wells screened in the Catahoula aquifer in La Salle Parish is 

presented in table 3. 

Cockfield Aquifer

The Cockfield aquifer is present throughout La Salle Parish 

but contains freshwater only in a roughly 3–7-mi-wide band along 

the northern parish line where the altitude of the base of freshwater 

ranges from about 300 to greater than 500 ft below NGVD 29 (fig. 

1). The Cockfield aquifer is overlain by clays of the VicksburgJackson confining layer throughout most of the parish (fig. 3) 

but outcrops at land surface near Olla (fig. 1) in the northwestern 
Table 3. Summary of selected water-quality characteristics of freshwater in the Upland terrace, Catahoula, and Cockfield aquifers in 

La Salle Parish, Louisiana (U.S. Geological Survey, 2013c). 

[Values are in milligrams per liter, except as noted. °C, degrees Celsius; PCU, platinum cobalt units; μS/cm, microsiemens per centimeter; SU, standard units; 

CaCO3, calcium carbonate; μg/L, micrograms per liter; <, less than; SMCL, Secondary Maximum Contaminant Level established by the U.S. Environmental 

Protection Agency (2012); NA, not applicable]

Temperature

(°C)

Color

(PCU)

Specific

conductance,

field

(μS/cm at

25 °C)

pH,

field

(SU)

Hardness

(as CaCO3

)

Chloride,

filtered

(as Cl)

Iron,

filtered

(μg/L

as Fe)

Manganese,

filtered

(μg/L

as Mn)

Dissolved

solids,

filtered

Upland terrace aquifer, 1939–84 (72 wells) 

Median 19.8 0 62 6.4 15 9.8 90 25 74

10th percentile 19.0 0 39 5.5 6 3.1 27 <10 53

90th percentile 20.5 10 193 6.9 60 50 700 87 151

Number of samples 12 39 39 39 72 72 38 34 39

Percentage of 

samples that do 

not exceed SMCLs

NA 97 NA 41 NA 100 87 82 97

Catahoula aquifer, 1945–83 (44 wells) 

Median 21.5 5 296 7.6 15 10 120 50 268

10th percentile 19.8 0 108 6.4 2 4.1 30 26 130

90th percentile 21.6 17 860 8.0 32 110 370 100 584

Number of samples 9 23 24 23 44 44 22 9 26

Percentage of 

samples that do 

not exceed SMCLs

NA 87 NA 83 NA 100 77 56 81

Cockfield aquifer, 1939–85 (39 wells) 

Median 21.0 100 1,130 8.4 8 35 110 30 622

10th percentile 20.0 5 655 7.7 0.5 11 56 <10 426

90th percentile 22.0 240 1,468 8.7 225 79 240 380 817

Number of samples 11 26 29 19 36 39 19 10 24

Percentage of 

samples that do 

not exceed SMCLs

NA 27 NA 79 NA 100 89 80 38

SMCLs

NA 15 NA 6.5–8.5 NA 250 300 50 500

Year

2000 2002 2004 2006 2008 2010 2012 2014

50

60

70

80

90

130

135

140

Well: La-124 Aquifer: Catahoula

Altitude of land surface: 161 ft above NGVD 29

Well depth: 365 ft below land surface

Well: La-172 Aquifer: Catahoula

Altitude of land surface: 180 ft above NGVD 29

Well depth: 97 ft below land surface 

Well: La-254A Aquifer: Cockfield

Altitude of land surface: 160 ft above NGVD 29

Well depth: 510 ft below land surface

Water level, in feet (ft)

Figure 4. Water levels in wells La-124 

and La-172 screened in the Catahoula 

aquifer and well La-254A screened in 

the Cockfield aquifer in La Salle Parish, 

Louisiana (see fig. 1 for well locations; 

U.S. Geological Survey, 2013a). Altitude 

of land surface and water levels 

are measured in feet (ft) above the 

National Geodetic Vertical Datum of 

1929 (NGVD 29).
corner of the parish. The aquifer dips to the southeast, and the 

altitude of the base of the aquifer ranges from about 400 ft above 

NGVD 29 in the northwestern corner of the parish to more than 

2,000 ft below NGVD 29 in the southeastern corner. Aquifer 

thickness ranges from about 400 to 800 ft in the freshwater area 

along the northern parish line (Ryals, 1984). 

Recharge to the aquifer is primarily from infiltration of 

precipitation in areas where the aquifer outcrops in La Salle, Winn, 

Caldwell, and Jackson Parishes and other parishes to the north. The 

direction of groundwater flow in the Cockfield aquifer in La Salle 

Parish is generally to the south or southeast (Brantly and Seanor, 

1996). Discharge from the aquifer is to local streams in the outcrop 

area, by evapotranspiration, by wells, and by seepage through the 

confining layer to overlying aquifers in areas where the aquifer is 

confined. The clayey confining layers above and below the aquifer 

have impeded flushing of saltwater from the aquifer downgradient 

(Rollo, 1960). The water level in well La-254A, located in 

northern La Salle Parish (fig. 1) and screened 510 ft below land 

surface in the Cockfield aquifer, fluctuates annually, but water 

levels have remained relatively stable since 2001 (fig. 4). 

State well-registration records listed 39 active wells screened 

in the Cockfield aquifer in La Salle Parish in 2014, including 

16 domestic, 14 industrial, and 9 public supply. Well depths 

ranged from 25 to 1,665 ft below land surface. Reported yields 

from wells screened in the Cockfield aquifer in La Salle Parish 

ranged from 3 to 335 gal/min (Louisiana Department of Natural 

Resources, 2014). Water withdrawals from the Cockfield aquifer 

in La Salle Parish totaled about 0.86 Mgal/d in 2010 (table 1) and 

included about 0.85 Mgal/d for public supply and 0.01 Mgal/d 

for rural-domestic use. A statistical summary of selected waterquality characteristics of freshwater from 39 wells screened in 

the Cockfield aquifer in La Salle Parish is presented in table 3. In 

general, samples did not exceed the SMCLs for concentrations of 

chloride, iron, and manganese but did exceed SMCLs for color and 

concentrations of dissolved solids.

Surface-Water Resources 

In 2010, about 0.10 Mgal/d of surface water were withdrawn 

in La Salle Parish (table 2). Notable surface-water bodies in the 

parish include the Little River, Bayou Funny Louis, Chickasaw 

and Little Chickasaw Creeks, Hemphill Creek, Trout Creek, Saline 

Lake, Muddy Bayou, Big Saline Bayou, French Fork Little River, 

and Catahoula Lake (fig. 1). 

Discharge data for streams in La Salle Parish are limited; 

however, during 1978–95, Hemphill Creek at Nebo (site number 

07373250; fig. 1) had an average daily discharge of 63 cubic feet 

per second (ft3

/s) from a drainage area of 35 square miles (mi2). 

During 1939–70, Bayou Funny Louis near Trout (site number 

07372500; fig. 1) had an average daily discharge of 123 ft3

/s from 

a drainage area of 92 mi2

 (U.S. Geological Survey, 2013b). During 

1958–96 and 1998–2011, the Little River near Rochelle (site 

number 07372200; fig. 1) had an average discharge of 2,182 ft3

/s 

from a drainage area of 1,899 mi2

 (U.S. Geological Survey, 2012). 

Water samples collected during 1964–86 indicated that water 

in the Little River near Rochelle is generally soft and generally 

does not exceed SMCLs for pH and concentrations of chloride 

and sulfate (table 4). Dissolved oxygen concentration is generally 

greater than 5 mg/L, which is considered the minimum value for a 

diversified population of fresh, warmwater biota, including sport 

fish (Louisiana Department of Environmental Quality, 2008). 

Catahoula Lake is the largest natural inland freshwater lake 

in Louisiana, covering more than 46 mi2

. The lake, located on the 

Little River (fig. 1), is a principal stopover and wintering area for 

hundreds of thousands of migratory waterfowl and shorebirds. The 

management plan for the lake includes maintaining seasonal trends 

of winter and spring high water and summer and fall drawdown, 

primarily to provide optimal habitat for migratory birds (Doyle 

and others, 2002). Water samples from Catahoula Lake, which 

were analyzed during the period 1976–78, are presented in table 4. 

The median value for hardness fell into the soft range, dissolved 

oxygen concentrations were generally greater than 5 mg/L, and the 

median value for manganese was 90 mg/L. 

References Cited 

Brantly, J.A., and Seanor, R.C., 1996, Louisiana ground-water map no. 9—

Potentiometric surface, 1993, and water-level changes, 1968–93, of the Cockfield 

aquifer in northern Louisiana: U.S. Geological Survey Water-Resources 

Investigations Report 95–4241, 2 sheets, accessed January 24, 2012, at http://

pubs.er.usgs.gov/publication/wri954241.

Doyle, T.W., Michot, T.C., and Wells, C.J., 2002, Modeling the bathymetry of 

Catahoula Lake—Specialized technology for wetland management: U.S. 

Geological Survey Fact Sheet 098–02, 2 p., accessed January 22, 2013, at http://

pubs.er.usgs.gov/publication/fs09802.

Fisk, H.N., 1938, Geology of Grant and La Salle Parishes: Department of 

Conservation, Louisiana Geological Survey Geological Bulletin no. 10, 246 p. 

Hem, J.D., 1985, Study and interpretation of the chemical characteristics of natural 

water (3d ed.): U.S. Geological Survey Water-Supply Paper 2254, 264 p., 

accessed February 20, 2013, at http://pubs.er.usgs.gov/publication/wsp2254.

Louisiana Department of Environmental Quality, 2008, Environmental Regulatory 

Code, Title 33, Part IX, Subpart 1: Baton Rouge, Louisiana Department of 

Environmental Quality, accessed December 27, 2012, at http:www.deq.louisiana.

gov/portal/tabid/1674/Default.aspx.

Louisiana Department of Natural Resources, 2014, Strategic Online Natural 

Resources Information System (SONRIS): Louisiana Department of Natural 

Resources database, accessed November 13, 2014, at http://sonris.com/.

Martin, Angel, Jr., and Whiteman, C.D., Jr., 1986, Generalized potentiometric 

surface of the Catahoula aquifer in central Louisiana, 1980: U.S. Geological 

Survey Water-Resources Investigations Report 86–4059, 1 sheet. 

Rollo, J.R., 1960, Ground water in Louisiana: Department of Conservation, 

Louisiana Geological Survey, and Louisiana Department of Public Works Water 

Resources Bulletin no. 1, 84 p.

Ryals, G.N., 1984, Regional geohydrology of the northern Louisiana salt-dome 

basin, part II, geohydrologic maps of the Tertiary aquifers and related confining 

layers: U.S. Geological Survey Water-Resources Investigations Report 83–4135, 

6 p., accessed December 27, 2012, at http://pubs.er.usgs.gov/publication/

wri834135.

Sargent, B.P., 2011, Water use in Louisiana, 2010: Louisiana Department of 

Transportation and Development Water Resources Special Report no. 17, 135 p. 

Seanor, R.C., and Smoot, C.W., 1995, Louisiana ground-water map no. 6—

Potentiometric surface, 1990, and water-level changes, 1974–90, of the 

Mississippi River alluvial aquifer in northeastern Louisiana: U.S. Geological 

Survey Water-Resources Investigations Report 95–4146, 2 sheets.

Sloss, Raymond, and May, H.G., 1961, Water, in La Salle Parish resources 

and facilities: Louisiana Department of Public Works and La Salle Parish 

Development Board, p. 47–57.

Smoot, C.W., 1988, Louisiana hydrologic atlas map no. 3—Altitude of the base of 

freshwater in Louisiana: U.S. Geological Survey Water-Resources Investigations 

Report 86–4314, 1 sheet, accessed December 27, 2012, at http://pubs.er.usgs.gov/

publication/wri864314.

U.S. Environmental Protection Agency, 1992, Secondary drinking water 

regulations—Guidance for nuisance chemicals: U.S. Environmental Protection 

Agency publication EPA 810/K-92-001, 4 p., accessed December 27, 2012, at 

http://water.epa.gov/drink/contaminants/secondarystandards.cfm.
Table 4. Summary of selected water-quality characteristics for Little River near Rochelle and Catahoula Lake at three locations in

La Salle Parish, Louisiana (U.S. Geological Survey, 2013c).

[Values are in milligrams per liter, except as noted. PCU, platinum cobalt units; μS/cm, microsiemens per centimeter; °C, degrees Celsius; SU, standard units; 

CaCO3, calcium carbonate; μg/L, micrograms per liter; SMCL, Secondary Maximum Contaminant Level established by the U.S. Environmental Protection 

Agency (2012); NA, not applicable]

Color 

(PCU)

Specific 

conductance, 

field (μS/cm 

at 25 °C)

Oxygen, 

dissolved

pH,

field

(SU)

Hardness (as 

CaCO3

)

Calcium, 

filtered 

(as Ca)

Chloride, 

filtered 

(as Cl)

Iron, 

filtered, 

(μg/L as 

Fe)

Manganese, 

filtered 

(μg/L as 

Mn)

Sulfate, 

filtered 

(as SO4

)

Dissolved 

solids

Little River near Rochelle, 1964–861

Median 100 314 7.0 6.7 30 8.1 56 380 185 17 225

10th percentile 40 81 4.9 6.1 14 4.0 8.9 180 71 8.6 73.6

90th percentile 200 1,750 10.0 7.4 90 20 620 940 445 69 1,734

Number of 

samples

225 234 140 211 202 196 204 36 32 205 214

Percentage of 

samples that 

do not exceed 

SMCLs

1 NA NA 68 NA NA 84 39 9 99 75

Catahoula Lake at three locations, 1976–782

Median 90 173.5 9.1 7.0 27 7.2 26 170 90 18.5 106

10th percentile 70 94.9 6.8 6.4 17.8 5.1 13 109 28 8.3 75.9

90th percentile 102 446.3 10.8 7.4 38.3 11 80.2 350 146 54.1 262.9

Number of 

samples

20 20 20 20 20 20 20 20 19 20 20

Percentage of 

samples that 

do not exceed 

SMCLs

0 NA NA 85 NA NA 100 85 26 100 100

SMCLs

15 NA NA 6.5–8.5 NA NA 250 300 50 250 500

1

Site number 07372200. 

2

Datasets from sites 312815092092000, 312910092072000, 313355092042000.

U.S. Environmental Protection Agency, 2012, 2012 Edition of the drinking 

water standards and health advisories: U.S. Environmental Protection 

Agency publication EPA 822-S-12-001, Office of Water, 12 p., accessed 

December 27, 2012, at http://water.epa.gov/action/advisories/drinking/upload/

dwstandards2012.pdf.

U.S. Geological Survey, 2012, Water-resources data for the United States, 

water year 2011, site 07372200: U.S. Geological Survey Water-Data Report 

WDR-US-2011, accessed January 18, 2013, at http://wdr.water.usgs.gov/

wy2011/pdfs/07372200.2011.pdf.

U.S. Geological Survey, 2013a, Groundwater levels for Louisiana: National Water 

Information System Web Interface, accessed January 15, 2013, at http://nwis.

waterdata.usgs.gov/la/nwis/gwlevels.

U.S. Geological Survey, 2013b, Surface-water daily statistics for the Nation: 

National Water Information System Web Interface, accessed September 25, 

2013, at http://waterdata.usgs.gov/nwis/nwisman/.

U.S. Geological Survey, 2013c, Water quality samples for Louisiana: National 

Water Information System Web Interface, accessed January 15, 2013, at http://

nwis.waterdata.usgs.gov/la/nwis/qwdata.

Whitfield, M.S., Jr., 1975, Geohydrology and water quality of the Mississippi 

River alluvial aquifer, northeastern Louisiana: Louisiana Department of Public 

Works Water Resources Technical Report no. 10, 29 p.

This fact sheet was published by the U.S. Geological 

Survey, in cooperation with the Louisiana Department 

of Transportation and Development (DOTD). Thanks 

are given to Zahir “Bo” Bolourchi, Director, Water 

Resources Programs, DOTD, who contributed to the 

content of the fact sheet.

By Vincent E. White and Lawrence B. Prakken

For additional information, contact: 

Director, USGS Lower Mississippi-Gulf Water Science Center

3535 S. Sherwood Forest Blvd., Suite 120

Baton Rouge, LA 70816

E-mail: gs-w-lmg_center_director@usgs.gov

Fax: (225) 298–5490

Telephone: (225) 298–5481

Home Page: http://la.water.usgs.gov

ISSN 2327-6916 (print)

ISSN 2327-6932 (online)

http://dx.doi.org/10.3133/fs20143089